check engine light comes on when down to 1/4 tank and goes off at 3/4 tank. Also Revs very high.

Asked by Dec 13, 2008 at 02:28 PM about the 2003 Chevrolet TrailBlazer LT

Question type: Maintenance & Repair

I have a chevy trailblazer that the check engine light comes on when down to around 1/4 tank of gas and then after refuel goes off when it is 3/4 tank full.  It also revs very high while driving, then it goes back to normal.  Any ideas?

7 Answers


given that you mention the high rev while driving and variations in fuel tank levels my guess, but I am not positive, may have to deal with something in the evaporative emission system

1 of 1 people found this helpful.

If the light is staying on until you fill back up, then stop by a parts store and get the code read...

4 of 4 people found this helpful.

Replace the fuel level sender in the fuel tank. A common wear out item on many vehicles. Had to do this on my friends 06 trailblazer and my wife's Isuzu Rodeo. True fix.

4 of 4 people found this helpful.

make sure your gas cap is tight. If that doesnt work, buy a new one.

2 of 2 people found this helpful.

Yes SanJoseTJK is likely right , the fuel level sensor id a vasriable resistor and likely has a worn out section where resistance is lost on the circuit when the fuel level reaches that level the vehicle requires a fuel level check before the vehicle computer (ECM) can run certain diagnostic tests ,when it runs the test and can not get a signal it turns on the check engine light and sets a DTC you need a code reader to be sure but will likley find 1 or more codes set for the fuel system

3 of 3 people found this helpful.

I have read that one can take the negative battery cable off for about 15 minutes and then put it back on to reset the check engine light and it will go off for a period of time anyway. Is this correct?


I suspect you have a problem with the gas tank vent system (EVAP).

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